Solid electrolytic capacitors (e.g., tantalum capacitors) have been a major contributor to the miniaturization of electronic circuits and have made possible the application of such circuits in extreme environments. Conventional solid electrolytic capacitors are often formed by pressing a metal powder (e.g., tantalum) around an anode lead, sintering the pressed part, anodizing the sintered anode, and thereafter applying a solid electrolyte, after which the resulting capacitor element is electrically connected to a lead frame at an anode termination and a cathode termination. In some embodiments, the anode termination contains a planar portion and an upstanding portion that is bent upwardly toward the capacitor element and welded to the anode lead extending from the anode. Meanwhile, the cathode termination may contain a planar portion and an upstanding portion, where the planar portion is connected to the capacitor element via a conductive adhesive or by welding. In any event, because the electrical connection at the anode termination is formed between the anode lead and the upstanding portion of the anode termination, the planar portion of the anode termination must generally be isolated from the capacitor element, such as via an encapsulating material, to prevent a short circuit, as discussed in more detail below. Such a capacitor can include a capacitor element having a lower surface, an upper surface, a front surface, a rear surface, and opposing side surfaces. An anode lead typically extends from the front surface of the capacitor element in a longitudinal direction. The capacitor also includes an anode termination, which can have a planar portion and an upstanding portion, as well as a cathode termination, which can have a planar portion and an upstanding portion. With such a capacitor, the capacitor element is typically electrically connected to the planar portion of the cathode termination via a conductive adhesive. Meanwhile, the anode lead is welded to the upstanding portion of the anode termination at anode lead slot to electrically connect the capacitor element to the anode termination.
Because the capacitor element is electrically connected to the anode termination via the weld or other suitable connection between the anode lead and the upstanding portion of the anode termination at anode lead slot, and because the planar portion of the anode termination and the planar portion of the cathode termination are typically formed in the same plane and have the same thickness, the capacitor element must generally be situated in an inclined position in order to ensure that the capacitor element can be sufficiently electrically isolated from the planar portion of the anode termination via encapsulating material, for example. The inclined position is maintained by forming the anode lead slot at a high enough location along the upstanding portion of the anode termination to raise the front surface of the capacitor element sufficiently above the planar portion of the anode termination. In this manner, the encapsulating material can fill the gap between the capacitor element and the planar portion of the anode termination to electrically isolate the capacitor element. Unfortunately, this technique is problematic in that it places a significant amount of stress on the anode lead weld or other suitable connection, as the single weld is essentially holding the entire capacitor element in an inclined position to create sufficient isolation between the capacitor element and the planar portion of the anode termination. Such an arrangement can weaken the connection between the anode lead and the upstanding portion of the anode termination and can place significant force on the anode lead, which, in turn, result s in an increase in the electrical series resistance (ESR) and leakage current (DCL) of the capacitor, which detrimentally affects the electrical performance of the capacitor.
As such, a need remains for a mechanically and electrically stable solid electrolytic capacitor where the forces placed on the anode lead and weld are minimized.